Transportation safety agencies have long said that using a handheld device such as a smartphone is a dangerous distraction to drivers. You pay less attention to the road, and reaction times are greatly slowed. But what about the continually growing presence of wearables like smartwatches? Surely they must be much less distracting than a phone, and with their heavy reliance on voice controls, they should be about as distracting as standard timepieces, right? Well, the UK's Transport Research Laboratory (TRL) says just the opposite.